Cable sleeve for a hand-held power tool

CROSS-REFERENCE TO RELATED APPLICATION

0001This application is a 35 USC 371 application of PCT/EP 2009/054965 filed on Apr. 24, 2009.

BACKGROUND OF THE INVENTION

00021. Field of the Invention

0003The present invention is based on a cable sleeve for guiding a cable in the inlet and outlet region of a hand-held tool.

00042. Description of the Prior Art

0005Corded hand-held power tools can usually be connected to a power source by means of a cable. The cable is encompassed by an essentially coaxial cable sleeve at the cable outlet opening from the housing.

0006The cable sleeve assures a relatively low bending angle of the cable at the outlet opening of the housing under all operating conditions, thus preventing a sharp bending of the cable went corresponding forces are exerted on it. This protects the cable from being damaged by extreme bending and also from other mechanical influences in the region in which it is enclosed by the cable sleeve.

0007During operation of the hand-held power tool, the cooling air of the electric motor is usually drawn into the housing from the outside through inlet openings, travels past the motor, and is blown out again through outlet openings. As a result, negative pressure is produced in the housing, which causes air from the outside to flow into the housing through all existing openings and gaps in corresponding regions, including through the gap between the cable and cable sleeve. This gap is present due to the relatively high production tolerances of the cable and cable sleeve and due to the fact that only a few types of cable sleeve are used for a wide variety of cables of different external diameters that are required due to the various voltage systems worldwide. For this reason, it is currently necessary to stock a plurality of cable sleeve types with various inner diameters.

0008Air drawn in by means of the cable sleeve conveys dust particles from the work environment into the interior of the power tool. For example when using an angle grinder, these dust particles are frequently metallic and on the inside of the housing, can settle on switches or other electrical, voltage-carrying elements. As a result, the conductive metallic particles can form bridges between the different voltage potentials. Corresponding arcing can result in breakdowns of the hand-held power tool and can be hazardous to the user.

ADVANTAGES AND SUMMARY OF THE INVENTION

0009Depending on the embodiment of the external and/or internal shape of the cable sleeve, the invention can perform a sealing action and can provide tolerance compensation. It is therefore not necessary to use a specific cable sleeve type for each country-specific design of the hand-held power tool, thus reducing the number of parts required. In addition, due to its new embodiment, the cable sleeve can simultaneously function as a power cord strain-relief element.

0010Because the cable sleeve encompasses the cable in a radially sealed, frictional, nonpositive fashion, water, dust, and the like cannot penetrate into the interior of the housing, particularly because the end of the cable sleeve oriented toward the housing has a ring-like sealing element that rests in a sealed fashion against the outer circumference of the cable.

0011Because the cable sleeve is provided with a helical sealing lip that protrudes radially inward, the cable can be inserted axially into a narrow cable sleeve by turning it like a screw.

0012The sealing action is improved by virtue of the fact that the cable sleeve has a plurality of ring-like sealing elements at its end oriented toward the housing.

0013The sealing action can be improved and the manufacture of the cable sleeve can be simplified by virtue of the fact that the ring-like sealing elements are embodied in the form of annular beads, particularly in the form of injection-molded O-rings composed of a material that differs from the material of the sleeve, in particular has softer elastic properties than it.

0014The sealing action for particular circumstances and special applications can be improved by virtue of the fact that the ring-like sealing elements are embodied in the form of hollow cylindrical plugs, in particular wedge-shaped plugs, that protrude into the hollow cylinder of the cable sleeve, particularly at its front end.

0015Another easy-to-install sealing variant is achieved by virtue of the fact that a smooth, cylindrical, hollow connecting piece of the cable sleeve protrudes axially into the interior of the housing and in the installed position therein, is encompassed in a contracting fashion so that a region of the hollow connecting piece rests in an annular, sealed fashion against the outside of the cable.

0016It is also possible to use conventional cable sleeves in a sealed fashion by virtue of the fact that clamping jaw-like parts, in particular parts belonging to the housing, are able to act on the hollow connecting piece.

0017The sealing action can be improved with extremely simple means by virtue of the fact that the housing is composed of housing shells, each of which has a clamping jaw-like part that belongs to a respective housing shell.

0018The sealing action can be improved with even simpler means by virtue of the fact that an annular shell part, in particular belonging to the housing, is able to act on the hollow connecting piece in the radial direction.

0019The sealing action can be improved with even simpler, conventional, inexpensive means by virtue of the fact that the annular shell-like part is embodied in the form of a tension sling, in particular a twistable wire and/or pipe clamp and/or cable strap.

BRIEF DESCRIPTION OF THE DRAWINGS

0020The invention will be explained below in conjunction with an exemplary embodiment and associated drawings.

0021<figref idref="DRAWINGS">FIG. 1</figref> shows a longitudinal sections through a hand-held power tool housing equipped with the cable and cable sleeve according to the invention,

0022<figref idref="DRAWINGS">FIG. 2</figref> shows another longitudinal section through the hand-held power tool housing equipped with the cable and cable sleeve according to the invention,

0023<figref idref="DRAWINGS">FIG. 3</figref> shows the cable sleeve according to <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, in a longitudinal section through a detail,

0024<figref idref="DRAWINGS">FIG. 4</figref> shows another cable sleeve with a helical radial inner sealing lip,

0025<figref idref="DRAWINGS">FIGS. 5 and 6</figref> each show a variant of the cable sleeve with a plurality of radial inner sealing lips,

0026<figref idref="DRAWINGS">FIG. 7</figref> shows a cable sleeve with a hollow, cylindrical plug as a sealing means,

0027<figref idref="DRAWINGS">FIG. 8</figref> shows a cable sleeve with a crushing region, which, acting as a sealing means, is acted on by clamping jaws,

0028<figref idref="DRAWINGS">FIG. 9</figref> shows a cable sleeve with a crushing region, which, acting as a sealing means, is acted on by an annular bracket-like sleeve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0029At its front end <b>30</b> situated inside the housing, a cable sleeve <b>22</b> depicted in <figref idref="DRAWINGS">FIGS. 1</figref>, <b>2</b>, and <b>3</b> has an annular, circumferential, inward-oriented radial sealing lip <b>28</b> that encompasses a cable, which is pulled into it, in an elastically pressing and therefore axially sealed fashion; the hollow cylinder <b>26</b> has a conical wall that becomes thinner toward its end <b>32</b>, which encompasses the cable <b>36</b> and shields it from the outside. The significantly thicker wall region in the vicinity of the front end <b>30</b> absorbs a greater bending moment than closer to the end <b>32</b> and therefore in the event of powerful bending forces acting on the cable <b>36</b>, prevents a sharp bending of the cable <b>36</b> relative to the longitudinal axis <b>24</b> of the housing <b>10</b>, i.e. by an acute angle of approximately 90° with a minimal bending radius, and thus also prevents breakage of the cable strands inside the cable <b>36</b>.

0030On the outside, the cable sleeve <b>22</b> is conventionally embodied and can be fixed in position by means of an external annular groove <b>34</b>, which is associated with a matching annular projection <b>16</b> of the housing <b>10</b>, and by means of its front end <b>30</b>, which is associated with a rib-like axial stop <b>18</b> of the housing <b>10</b>. The housing wall <b>11</b> of housing <b>10</b> constitutes a cable sleeve outlet opening <b>14</b>, which encompasses the cable sleeve <b>22</b> through which the cable sleeve <b>22</b> protrudes outward, and as it does so, conveys the cable <b>36</b> to the inside.

0031The sealing, insertion, and withdrawal properties of the cable in relation to the cable sleeve <b>22</b> can be selected through the embodiment of the sleeve's angle in the region of the sealing lip. If the sealing lip <b>28</b>, as depicted in <figref idref="DRAWINGS">FIG. 3</figref>, has a saw-tooth structure, it is safe to assume that the cable sleeve <b>22</b> has a relatively low, assembly-friendly cable pull-in force as compared to a higher pull-out force. This facilitates strain relief. To this end, it is also possible to provide corresponding grooves or cams on the cable <b>36</b>.

0032<figref idref="DRAWINGS">FIG. 4</figref> shows a cable sleeve <b>220</b> having a front end <b>300</b> and an end <b>320</b>. The cable sleeve <b>220</b> is provided with a helical inward-oriented radial sealing lip <b>280</b> that can have a stepped inner diameter for a use with cables of different diameters. In this connection, when the cable sleeve <b>220</b> is used for large cable diameters, sealing lips that are too tight can be removed mechanically or thermally or in some other way. According to this principle, the cable <b>36</b> is screwed into the cable sleeve <b>220</b> like a screw into the thread of a nut. In this case, it is possible for a cable sleeve <b>220</b> that is manufactured in one piece to have material combinations between the conventional sleeve region and the sealing region.

0033In a variant of the cable sleeve <b>220</b> with a helical, stepped sealing lip, closer to a more elastic or more stretchable region of the hollow cylinder <b>260</b>, it is not necessary to remove excessively large sealing lips because they are able to move radially out of the way along with the hollow cylinder <b>260</b> and its wall.

0034The cable sleeves <b>2200</b>, <b>22000</b> shown in <figref idref="DRAWINGS">FIGS. 5 and 6</figref> each have two parallel, radial, inner sealing lips <b>2800</b>, <b>28000</b> constituted by integrated annular beads or O-rings composed of a material that is the same as or different from the material of the respective cable sleeve. Like the helical sealing lip according to <figref idref="DRAWINGS">FIG. 4</figref>, these can each have a different respective inner diameter for different thicknesses of cable; for thicker cables, excessively tight sealing lips can be removed mechanically or thermally or in some other way. A cable that has been pulled in is elastically enclosed in a sealed fashion in accordance with the active principle of an O-ring. Other shapes of the annular bead—e.g. rectangular, square, or elliptical—and/or other materials of a one-piece cable sleeve for the conventional sleeve region and the sealing region are also conceivable.

0035The advantage of this variant is the ability to select a suitable size of the O-rings; it is also possible to select from a broad range of materials for the sealing means. In these cable sleeves, it is also advantageous for the sealing cross-sections to be embodied as rectangular, square, elliptical, saw-toothed, etc.

0036The front end <b>301</b> of the cable sleeve <b>221</b> shown in <figref idref="DRAWINGS">FIG. 7</figref> has an elastic, hollow, cylindrical wedge element <b>281</b> that is pressed into the inside of the hollow cylinder <b>263</b> of the cable sleeve <b>221</b> and correspondingly fixed in place, e.g. by means of frictional, nonpositive engagement, a mechanical undercut, a rib on the housing, or glue. The pressing action slides the wedge element in a sealed fashion into the pre-existing gap between the cable sleeve and the cable, not shown. Another variant of a cable sleeve manufactured of one piece in accordance with the design shown in <figref idref="DRAWINGS">FIG. 7</figref>, equipped with an integrated cone, is not shown in the drawing.

0037The front end <b>302</b> of the cable sleeve <b>222</b> shown in <figref idref="DRAWINGS">FIG. 8</figref> has a protruding region <b>29</b> similar to a pipe-connecting piece, with a narrow wall thickness. This region <b>29</b> performs its sealing function in relation to an inserted cable once a radial force is exerted on it from the outside. For this purpose, opposing ribs <b>13</b> are integrated into the two shells <b>12</b> (one shell <b>12</b> is shown in <figref idref="DRAWINGS">FIG. 1</figref>) of the housing <b>10</b> and when the shells <b>12</b> are assembled, act on the region <b>13</b> from the outside like a pair of pliers, deforming it in a cross-sectionally constricting fashion, producing a seal in relation to the inserted cable. Alternatively, it is also possible for a plurality of ribs to be arranged one after another and laterally offset from one another, from the one shell to the other shell. By means of this measure, the additional deformation of the power cord could function like a strain-relief element.

0038The front end <b>303</b> of the cable sleeve <b>223</b> shown in <figref idref="DRAWINGS">FIG. 9</figref> has a protruding region <b>291</b> similar to a pipe connecting piece, with a narrow wall thickness like the cable sleeve according to <figref idref="DRAWINGS">FIG. 8</figref>. This region <b>291</b> performs its sealing function in relation to an inserted cable once a radial force is exerted on it from the outside. For this purpose, a crushing element <b>11</b> is provided, which acts on the region <b>13</b> from the outside, deforming it in a cross-sectionally constricting fashion, producing a seal in relation to an inserted cable. The crushing element can, for example, be a twistable wire, pipe clamp, cable strap, or similar device. According to this principle, the seal is achieved by compressing and constricting the sleeve from the outside in the direction toward the power cord. Another advantage is the possibility of prefabricating the combined unit composed of the sleeve and cable.

0039Furthermore, gluing the cable sleeve to the cable would produce a sealed, strain-relieving cable inlet. Filling the intermediate space between the cable sleeve and cable with a corresponding foam material is also a conceivable way to achieve a durable, sealed connection. As another variant, a cable sleeve that is vulcanized onto the cable is provided and/or the cable sleeve is injection molded around the cable and/or the cable sleeve is embodied in the form of an elastic shrink sleeve.

0040The above-mentioned cable sleeve principles can be partially combined with one another. This yields additional variants. Corresponding sealing means can be situated in the hollow cylinder <b>26</b> over the entire length of the cable sleeve and embodied in accordance with the production process and assembly process.

0041In other variants, the cable sleeves can also be embodied of multiple parts or in the form of shells in order to facilitate assembly.

0042The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.